Final answer:
The best example of fluid intelligence is the ability to quickly recognize relationships between words, as it involves problem-solving and identifying patterns in new information.
Step-by-step explanation:
Fluid intelligence is defined as the ability to see complex relationships and solve problems. Therefore, the best example of fluid intelligence among the options provided would be B. the ability to quickly recognize relationships between words, as this option involves processing new information, identifying patterns, and solving problems that are not based on previously acquired knowledge.
In contrast, other options such as extensive knowledge of computer programming, knowing the chronological order of British monarchs, or reading an electrocardiogram relate more closely to crystallized intelligence, which is characterized by the ability to retrieve and use learned knowledge and experiences.